Extreme weather can damage transmission lines and substations, making it impossible to bring in additional electricity.
Hurricane Ida showed why this matters.
The answer to bolstering power grids is not just to build more high-voltage transmission lines. It is also important to harden the transmission corridors that already exist so they can withstand extreme weather and be restored more quickly after a disaster.
In New Orleans, that is already shaping investment. Entergy New Orleans, the city’s main electric utility, has an accelerated grid-hardening plan that aims to replace existing utility poles with more fortified poles to withstand higher winds and selectively move some lines underground in high-risk areas. The first phase, scheduled through 2026, covers about 63 miles of power lines at a cost of $100 million.
At the federal level, the Federal Energy Regulatory Commission has required transmission providers to report how they assess risks to transmission assets, how those risks affect system operations and how they plan to reduce them, including under extreme heat and cold.
The hidden regulatory rules for sharing power
When the power goes out in one area, a nearby grid may look fine and keep its own lights on, but that does not mean its surplus power can be easily shared. Federal standards require transmission providers to have enough electricity available in reserve to serve their own local homes and businesses safely. In plain terms, only excess electricity above that safety threshold can realistically be treated as power available to help neighboring grids during an outage.
Decisions also have to be made quickly, and the logistics for sending power from one company have to be arranged before the blackout begins. The grid facing power shortages must know which sources will send extra power, which lines can carry it and what to do if the transfer creates overloads elsewhere.
The emergency operations manual used by PJM, which coordinates electricity flows across large parts of the Midwest and mid-Atlantic region, says operators are expected to act immediately when their power demand exceeds the supply to stabilize the grid. If the shortage lasts too long, protective systems begin disconnecting parts of the grid to stop a wider collapse. Once those systems are disconnected, even power that arrives later may no longer reach the areas where it is needed most.
Neighboring grids to the rescue
In early September 2022, a brutal heat wave pushed California’s power grid to the brink. On Sept. 6, the state hit an all-time record power demand of 52,061 megawatts.
That same evening, when the system was most strained, a crucial lifeline of about 8,000 MW of electricity flowed in from neighboring areas. This massive external support met 12.5% of the local demand, successfully maintaining the power supply for millions.
Analyses after the heat wave confirmed what had averted the crisis. The California Independent System Operator, or CAISO, concluded that “imported electricity from neighboring balancing authorities played a key role in maintaining system reliability” during those critical hours.
Crucially, this rescue relied on established sharing agreements. Beyond prescheduled transfers, CAISO reported that power generators in the Western Energy Imbalance Market – a system launched in 2014 to help Western power systems share electricity in emergencies – dynamically delivered an extra 1,000 MW of emergency power.
That event proved how having real-time, cross-regional coordination mechanisms already in place can ultimately save a grid under siege. Similar arrangements already exist elsewhere in the United States. PJM and MISO, the Midcontinent Independent System Operator, have a process for scheduling electricity flows when the regions know help will be needed. Utilities in the Southeast use an exchange platform to trade power closer to the time it is needed.
While different regions use different designs, the broader lesson is the same: Outside help is most likely to work when the grid has a usable transmission path, spare electricity to share and a system for moving that power before the emergency begins.
Yan Wen, a postdoctoral research scientist in electrical engineering at the University of Tennessee, contributed to this article.
Sufan Jiang, Research Scientist, University of Tennessee; Nanyang Technological University and Fangxing Fran Li, Professor of Electrical Engineering, University of Tennessee
This article is republished from The Conversation under a Creative Commons license. Read the original article.
